A pendulating integrating gyroscopic accelerometer (PIGA) is a type of accelerometer that can measure acceleration and simultaneously integrate this acceleration against time to produce a speed measure, as well. The PIGA's main use is in inertial navigation systems (INS) for guidance of aircraft and most particularly for ballistic missile guidance. It is valued for its extremely high sensitivity and accuracy in conjunction with operation over a wide acceleration range. The PIGA is still considered the premier instrument for strategic-grade missile guidance, though systems based on MEMS technology are attractive for lower performance requirements.
However, the PIGA has significant size and weight that make it non-optimum in many applications. Also, the PIGA is a mechanical mechanism requiring high-precision machining tolerances and, thus, is very expensive to manufacture.